The present invention relates to tubular bumper beams for vehicles.
Apparatus and methods are disclosed in U.S. Pat. Nos. 5,092,512 and 5,454,504 for rollforming and sweeping (i.e., longitudinally curving) tubular bumper beams for vehicles. However, further improvements are desired. For example, it is desirable to integrate components and features into the beam, such as the vehicle mounting structure, without adding to the number of secondary operations that must be performed on the beams. Further, it is desirable to provide beams having different flexural properties along their length. For example, it is preferable in some beams to have increased flexibility in a center area and at end areas of the beam, but increased stiffness at vehicle mounting locations of the beam. Still further, it is desirable to add style and irregularities along a length of the beam in some vehicle models.
Accordingly, a bumper and method are desired solving the aforementioned problems and providing the aforementioned advantages.
In one aspect of the present invention, a bumper construction for vehicles includes a tubular beam having a length and a longitudinal cross section that varies along the length. The tubular beam includes front and rear walls that have center sections with longitudinally extending arcuate surfaces defining different radii that extend around different vertical axes, and includes top and bottom walls that connect tee front and rear walls.
In another aspect of the present invention, a bumper construction for vehicles includes a tubular beam having a length and a longitudinal cross section that varies along the length. The tubular beam includes a rear wall having a center section that defines a longitudinally extending arcuate surface, having a mounting section on each end of the center section that defines a flat mounting surface, and having a corner section on each outer end of the respective mounting sections that sweeps rearwardly from the flat mounting surface. The tubular beam further includes top and bottom walls that connect the front and rear walls and that extend generally horizontally when in a car-mounted position.
In another aspect of the present invention, a method includes steps of forming a tubular beam having a length and a longitudinal cross section that varies along the length, including forming front and rear walls to have center sections with longitudinally extending arcuate surfaces defining different radii that extend around different vertical axes, and forming top and bottom walls that connect the front and rear walls.
In another aspect of the present invention, a method includes steps of rollforming a tubular beam with a constant longitudinal cross section, and reshaping portions of the tubular beam at locations spaced from ends of the tubular beam to form a non-uniform cross section along a length of the tubular beam.
In another aspect of the present invention, a method includes steps of providing a longitudinally curved tubular beam with a constant longitudinal cross section. The tubular beam has a front wall and a back wall spaced from the front wall. The front wall has top, bottom, and center areas. The method further includes outwardly forming the center area in the front wall along different portions of the tubular beam to form a non-uniform cross section along the length.